If you set the phone to upload photos to skydrive. There is a way to mount a drive right to skydrive on your desktop. Pictures sent right to my computer so nice.

in settings, you can allow your phone to upload your photos directly to skydrive.

you can tag people in photos when you upload it to facebook

you can share onenote documents with people (using skydrive), and it will sync to everyone’s phone/skydrive, makes it super easy to send notes around to a group!

Here's one that is not obvious. You can filter in local scout! Click on the small green text under eat+drink, see+do etc.

You can have Internet access on your phone when you are connected to Zune via USB. One simple way to limit your data charges.

When using email, touching the far left of the screen (next to the email title) brings out check boxes to select and manipulate multiple emails.

"pin to start" from within internet explorer snaps a screenshot for the start screen tile. Zoom into a nice looking part of the page (ie:wpcentral logo at top of page) before "pin to start" for a better looking start screen tile.

Keyboard related function:

If you double tap the shift button, enables caps lock until you single tap shift button again.

Press and hold alphabet keys to bring up accent characters.

You can tap and hold on the number key on the bottom left and then slide your finger all over the numbers and just let go. Basically you never have to toggle the numbers key. Most just think you can only do that on a few keyboard buttons like punctuation.

Pressing back with the soft keyboard open will close the keyboard.

tapping and holding on keys on the keyboard allows you to add less-used symbols/letters

when typing, double tapping space bar adds a period, adds a space, and capitalises the next letter.

APPS related Function:

There is an app called Stop The Music! That will remove any music that may be listed on he volume bar so that it goes back to its small size.

holding back button allows for multitasking

when you have 41 or more apps, the letter navigation pops up (just like in people hub)

onenote is a good alternative to a todo app, it allows you to have checkbox lists, add images or voice notes, and syncs it to skydrive automatically for you

Continue hitting the back button will clear all your background running Apps. If you want to close a specific App running in the background, Hold the back button, select the app in the card view and then hit the back button.

Hitting back (starting with the left most tab in multitasking) until you hit the home screen will close all apps/tasks.

Flipping the phone to landscape view while using the calculator will give more functions.

In the calculator, turning the phone clockwise gives you different options than turning the phone counter-clockwise.

To make a checkbox "to-do" list style note in OneNote - Highlight what you want to have check boxes and push the check box button at the bottom.

There's no native way to pin WiFi on&off switch to main screen, but with ConnectivityShortcuts app you can pin tiles for toggling your connections. Data & WiFi are most useful in my opinion, but there is also Bluetooth and Airplane mode.
I often switch from data to WiFi to save on traffic and instead of rummaging through Settings every time, I just use the main screen shortcuts.

Core OS related Function:

You don't need to swith off wifi. It turn off after some seconds after you put your phone in SleepMode.

If you tap and hold on a tile, you can rearrange the order of all your tiles, not just the one you tapped on. Just single-tap on any other tile and move it around. A tap on either side of the tiles will exit the rearrange mode.

After pressing the arrow to access the list of apps, you can press again (in the same position) to bring up the alphabetical menu. You can press to the right of any blue letter to access the menu; you don't have to press on the icon itself.

the same goes for accessing the three dot menu, you don't have to press the dots, you can press on the other side of the screen too

If you go to settings and go to "ease of access" which is the handicap settings and turn on "speech for phone accessibility" when the phone rings the name of the person that is calling will be repeated while the phone rings letting you know who is calling. It also expands the voice options for texting.

in the calendar month view touch the name of the month and then you can jump to any month in any year

when you browse your photos by date, touch the name of the month and the year, and you will get a full list of months and years

After a few seconds, all the connections and battery life on the top of the screen disappear. Tapping the same area will pop them all back up.

Pressing the back button gets rid of the volume bar quickly.

Holding start button lets you use voice. Hold the 'Windows' button and when 'listen' comes up say 'help' and it will explain all the options you have for voice commands.

holding camera button when your phone is locked opens up the camera ( witch you can also turn off )

Depending on what your screen brightness is set to, it will change the maximum brightness your screen can go to on AUTO brightness.

IF connected to BT (Bluetooth) your phone will read out your SMS and give you the option to use voice to txt to reply.

People HUB Functions:

Within the address book, you can create groups and add add people within those groups. I have Family, Close Friends and Co-Workers. I can view all their social activity at one place. I can also pin these group/s as a home screen tile.

In the address book view, if a person has multiple iterations of their info from Live, Facebook, Twitter, Gmail, Linkedin, etc. You can combine them all by using the 'Link' icon from within their profile view. WP actually gives you suggestions on the names from your address book. This way, there is only one iteration of their contact which combines all the different profiles of that person.

Zune player Functions(Phone+pc):

On the now playing screen in Zune you can tap below the song playing and it will list upcoming songs.

While listening to any kind of music, changing the volume brings up the expanded volume bar with the currently playing audio. Tap the title and it will take you into whatever app is playing the music.

You can show info for what's currently playing in the music+video app on your lock screen. Turn the setting on under lock+wallpaper.

When a song is playing in the Zune app you can tap the artists name and go to their albums list.

If your playing music in shuffle mode and add a song to now playing through a tap and hold, it will be the next song to play. Same thing for an album

On the now playing screen in Zune you can tap below the song playing and it will list upcoming songs.

If you pin an artist to the home screen, you get the double tile.

If you stop playing music on the Lumia 900, the music on the volume bar will disappear after a short period of time. Unlike with older WP phones where it stayed until phone reset

In Zune player, if you hold down the next track button and it will start to fast forward...same with rewind just hold down the previous track button.

Holding down a blank space while listening to radio on the headphones, gives you the option to use the speakers instead. Currently listening to music that way

how do you repeat just one song? Double tap on repeat. A little number "1" will appear next to it symbolizing that only that one song will only play.

You kind of cover this but it's more specific. You can tap and hold on the number key on the bottom left and then slide your finger all over the numbers and just let go. Basically you never have to toggle the numbers key. Most just think you can only do that on a few keyboard buttons like punctuation.

Continue hitting the back button will clear all your background running Apps. If you want to close a specific App running in the background, Hold the back button, select the app in the card view and then hit the back button.

In the address book view, if a person has multiple iterations of their info from Live, Facebook, Twitter, Gmail, Linkedin, etc. You can combine them all by using the 'Link' icon from within their profile view. WP actually gives you suggestions on the names from your address book. This way, there is only one iteration of their contact which combines all the different profiles of that person.

Within the address book, you can create groups and add add people within those groups. I have Family, Close Friends and Co-Workers. I can view all their social activity at one place. I can also pin these group/s as a home screen tile.

Continue hitting the back button will clear all your background running Apps. If you want to close a specific App running in the background, Hold the back button, select the app in the card view and then hit the back button.

Am I the only one who thinks that this should not be included, as it is spreading misinformation and further bolstering a misconception and its continued and unneeded spreading?

It does do what is being described in there, namely that it removes the Apps from the Fast-App-Switching/Multitasking view, but it does not what it says it is supposed to do, namely "close" the Apps. The Apps are all already closed when you are not in them, so there is absolutely no need to do that. :)

Im still not seeing this functionality I have had the same music in the Volume bar sense 4 O'Clock. What exactly are you doing to get this to happen?

I just tested it. Happens for me on my 1st gen phone, when the music player gets moved out of the Multitasking view. Try it out. Look at how many cards there can be, then Play a song and pause it. Then open up random things so that the music player gets pushed to the last spot. It's still there. Then after that open up 1-3 more apps and it will be pushed out. I just didn't check whether it was after it was just pushed out or after I opened an additional 1-2 Apps after it was already just pushed out.

Also, there is always Stop The Music. When you open the App, you can pin the stop button to the start screen.